It's not often that the last two World Series winners meet up in the postseason, but that will be the case in this year's National League Championship Series, as the defending champion St. Louis Cardinals and 2010 winner, the San Francisco Giants, square off in the best-of-seven set starting Sunday at AT&T Park.

The previous two World Series winners haven't met in the postseason since the New York Yankees and Milwaukee Braves dueled in the 1958 Fall Classic.

San Francisco has played the Cardinals twice before in the playoffs. St. Louis edged the Giants in a thrilling seven-game series in 1987, but San Francisco got its revenge in 2002 with a five-game win in the LCS.

These teams split six regular season meetings this year, but both enter riding an incredible wave of momentum. The Giants, of course, became the first NL team to rally from an 0-2 series deficit and win an NLDS, while the Cardinals came back from falling behind 6-0 in their decisive fifth game with the Nationals.

San Francisco is in the NLCS for the second time in three years and the Cardinals are making their seventh appearance since 2000.

As an introduction to this NLCS matchup, let's take a look at the keys to winning the series for both clubs:

ST. LOUIS CARDINALS

1. CARLOS BELTRAN

Carlos Beltran was brought into replace Albert Pujols and actually put up about the same numbers, as he hit .269 with 32 home runs and 97 RBI.

As good of a player as Beltran is in the regular season, he is quite simply one of the best postseason hitters in this generation and that was certainly the case in the series with the Nationals, as he hit .409.

Beltran, who owns an all-time best .817 career postseason slugging percentage also joined Babe Ruth as the only players to reach base five times in an elimination game.

2. CHRIS CARPENTER

St. Louis may have the biggest weapon in this series in righty Chris Carpenter.

The former Cy Young Award winner missed most of the season with a shoulder injury, but returned late in the season and to make three starts. But, like Beltran has been one of the better postseason players in recent memory.

He shut out the Nationals over 5 2/3 innings in his lone NLDS start and is 10-2 lifetime in the playoffs with a 2.88 ERA in 16 starts.

3. MOJO

It seems like we've been here before with this St. Louis Cardinals team.

Last year they overcame a 9 1/2-game deficit and secured a playoff spot on the final day of the regular season, only to parlay that into their 11th World Series title.

And just like last year, in the Nationals, the Cardinals have taken out the team with the most wins in the regular season. Last year, St. Louis topped Philadelphia in a do-or-die Game 5 on the road in the NLDS.

Although, they didn't have to overcome a six-run deficit last season like they did on Friday to win.

It doesn't matter what anyone else may think of this Cardinals team, the 25 men on the roster believe they can win it all again. You want to bet against them?

SAN FRANCISCO GIANTS

1. TIM LINCECUM

Nobody was more important to the Giants in their five-game win over Cincinnati than two-time Cy Young Award winner Tim Lincecum, who was remarkable in two relief outings.

After an awful season that saw him go 10-15 with a 5.18 ERA, Lincecum was demoted to the pen, but the Freak answered the call, going 1-0, while allowing just one run in with eight strikeouts in 6 1/3 frames.

Now Lincecum could wiggle his way into a start in this series, as Barry Zito struggled in his outing. Madison Bumgarner will go for the Giants in Game 1, followed by Ryan Vogelsong and Matt Cain the third game.

Although manager Bruce Bochy hasn't decided on a Game 4 starter, you can bet your last dollar that he goes with Lincecum.

2. BUSTER POSEY

The Giants don't offer much in the offensive department, but they do have one player that pitchers worry about in MVP candidate Buster Posey.

Posey didn't do much in the first four games against the Reds, but his grand slam in Game 5 set the tone in the win. And let's not forget, despite his .211 NLDS average, this is a player who was the NL's leading hitter at .336 with 24 home runs and 103 RBI during the regular season.

San Francisco, though, will need more from him in this round if they are going to advance.

3. LOOK INTO EACH OTHER'S EYES

Hunter Pence was acquired near the trade deadline to help the Giants' woeful offense, but hit just .219 in 59 games.

However, he has become the team's inspirational leader and manager Bruce Bochy has credited him as the guy who got the team fired up when they were in an 0-2 hole against the Reds prior to Game 3.

Pence's fiery football like scrums are now a part of the pregame ritual and his "look into each other's eyes" has become a rallying cry for the team.